Inorganic Constituents. On April 24, 1992, and January 11, 1995, the IEPA issued supplemental permits to ANL-E that, in part, approved a groundwater monitoring program for the sanitary landfill. The program will be capable of identifying any releases from the facility and demonstrating compliance with the applicable groundwater quality standards. Under the January 1995 supplemental permit, IEPA chose 13 groundwater monitoring points (800161, 800162, 800163D, 800171, 800173D, 800181, 800183D, 800191, 800192, 800193D, 800201, 800202, 800203D) to be sampled on a quarterly basis commencing January 1995. Parameters to be monitored include field parameters, routine indicator parameters, inorganic parameters, and volatile organic parameters. Volatile organic parameters are to be monitored only during the second quarter of monitoring. Routine indicator parameters are field-filtered prior to analysis and are collected each quarter. Inorganic parameters are unfiltered prior to analysis and are collected only during the second quarter.

ANL-E chose a conservative approach for evaluating the inorganic monitoring results by selecting as the standard of comparison the Illinois Groundwater Quality Standards for Class I: Potable Resource Groundwater, 35 IAC Section 620.410. The most common constituents at levels above the WQS (see Table 6.23) are chloride, iron, TDS, and manganese. This is consistent with results reported in prior years using the previous well monitoring network.

Wells 800163D, 800173D, 800191, 800193D, and 800203D consistently exceeded the WQS for chloride. Chloride levels ranged from 106 mg/L to 547 mg/L in these wells. The iron WQS was exceeded only once for a filtered sample at well 800203D. This appears to be an isolated result, and the cause is unknown. During the second quarter when unfiltered iron samples are required, the iron WQS was exceeded in wells 800173D, 800181, 800191, 800192, 800193D, 800201, and 800203D. The iron levels for these samples ranged from 5,280 mg/L to 24,300 mg/L. The manganese WQS was consistently exceeded in wells 800161, 800162, 800171, 800173D, 800181, 800191, 800192, 800201, and 800202. Manganese levels in these wells ranged from 40 mg/L to 1,440 mg/L. The total dissolved solid WQS was exceeded each quarter in well 800171, and the levels ranged from 1,087 mg/L to 1,409 mg/L. The chromium and nickel WQSs were exceeded during the second quarter in well 800181. Chromium and nickel are required to be monitored only during the second quarter.

Organic Constituents. No exceedances of the organic WQS were noted during 1995. Methylene chloride was the most consistent parameter detected during 1995; it was detected in each well at least two or more quarters. Levels were low and ranged from 1 g/L to 12 g/L. Acetone was detected infrequently in wells 800162, 800163D, 800173D, 800183D, 800193D, 800202, and 800203D. Acetone levels ranged from 2 g/L to 66 g/L. Acetone was also found in the blank samples during the first, third, and fourth quarters; low-level acetone results during these quarters may be indicative of laboratory contamination. Toluene was found in trace amounts in wells 800162 and 800163D. Trace levels of 2-butanone were found in wells 800163D, 800173D, and 800183D. Chloroethane and cis-1,2-dichloroethene were detected at trace levels in well 800171 only one quarter, and trace levels of trichloroethene were detected for three quarters. No semivolatiles, PCBs, pesticides, and herbicides were detected in the 800 Area Landfill wells during 1995.

Radioactive Constituents. Samples collected from the 800 Area sanitary landfill monitoring wells were also analyzed for hydrogen-3. The results are shown in Tables 6.27 to 6.39. Although the disposal of radioactive materials was prohibited in the sanitary landfill, very low concentrations of hydrogen-3 were detected in wells 800161, 800171, and 800192, probably because of inadvertent disposal of radioactivity in ANL-E trash. However, the presence of hydrogen-3 as tritiated water allows information to be obtained on the subsurface water flow pathway in the sanitary landfill area. The data indicate that the principal direction of subsurface water flow is to the south-southeast, with a small component to the northwest. This is consistent with the estimated subsurface water flow based on water level measurements and general flow patterns in the area.